Transmission Oil Leak

[Stein]

Hi all,

I recently discovered that my Polo GTI seems to be leaking oil from around the large black cover on the transmission and possibly from what looks to be one of the covers underneath.

This is the black cover on the side of the transmission, it looks to be leaking from the rubber gasket.

IMG-20200518-143221 — ImgBB

There might also be oil coming from this other black cover.

IMG-20200518-143237 — ImgBB

Does anyone know if this seems likely and if so where can I go about finding the part numbers I need to get some replacements? I'm looking into getting a workshop manual for the torque specifications anyway so I'd imagine they'd be in there.

Thanks heaps.

Edit:

If anyone comes across this thread in the future looking for the same gasket, VW's part number is 02R301215. It ran me about $65.

[h100vw]

Dropbox - 02Rgearbox.pdf - Simplify your life
Probably simplest to go to VW for the seals.

[Stein]

Dropbox - 02Rgearbox.pdf - Simplify your life
Probably simplest to go to VW for the seals.

That's brilliant, thanks Gavin. Only just realised that there's a sticky though.

Have you got any recommendations for a replacement oil? I read that some boxes develop a grinding between 1st and 2nd gear, my Polo only has 53,000KM on the clock and was hoping to stave off any issues. 2L of Nulon fully-synthetic 75W-90 was on the cards at the moment.

Thanks again!

[h100vw]

Any 75w90 synthetic would be an improvement on stock.

[Stein]

Any 75w90 synthetic would be an improvement on stock.

Cheers, will get on it.

[sambb]

can vouch for that. I was running 75W90 Motul and recently did an oil change after 2 years. Glad I did because the oil was pretty foul and gluggy coming out. I replaced it with OEM 75 monograde because I had two bottles of it sitting on the shelf and now I notice that the synchros are inclined to crunch slightly if I rush a gear change and also when I get 1st gear wheel spin the LSD is much more audible in its action. 75W90 is the go.

[simon k]

is there a defined service interval? I've done 45000km since I bought my Polo and haven't changed it - it wouldn't surprise me if it hasn't ever been changed

[sambb]

they were meant to "filled for life" I think? which is rubbish really. Mine was putrid when I first dumped the from the factory oil in my first box and same again when I dumped a second set of oil that had worked harder on track etc with the LSD and it was foul too. I'd do it. Its dead easy and your synchros will thank you.

[simon k]

gotcha...

[sambb]

You'll need a big in-hex for the empty and fill plugs and a small pump bottle to get the fluid in. Its been talked about on here before but you need to get the passenger side wheels up on 4 X 2 timbers or something so that the box will take the 1.9-2.0L that it needs. Without that it'll be dribbling out the fill port with only 1.7L in there.
I had Redline MTL in my first box for 2 years which came out looking ok before I got the wavetrac built into it. Synchros liked that oil. That box was refilled with Motul 300 75W90 and that was the stuff that came out with chunks and globs in it after the same time period. Synchros were happy with that too but I think maybe the LSD turned the oil into whipped cream. Now I have stock 75 monograde and straight away I can hear the diff action and the synchros are protesting sometimes. So I can only recommend Redline MTL out of those three.

[simon k]

thanks Sam, I appreciate the extra detail. I did a search and read about the 17mm hex - I'll make something or do the nut and bolt trick or use a mini wheel nut (double the thickness of a normal nut), no point buying a big ass hex bit when I'll hardly use it.

I do wonder what's in the box now though, maybe it is something good because it takes a lot of abuse with out any synchro crunches. Maybe I'm just good at sympathetic gearchanges after living with 50+ year old gearbox designs for all of my driving life.

but... oil argument alert! google says that Redline MTL is 75W80, and Gav says 75W90 - uh oh...

[h100vw]

FYIs
G 070 726 A2 is the VW part number.
Top Tec MTF 5100 75W is going in my box tomorrow. This says its for 7 speed dry clutch DSGs but that is just the gear side of the box, not the mechtronics! $16 a litre at trade

High Performance Gear Oil (GL4+) SAE 75W-90 This come up with th eproduct finder. $23 a litre at trade

I'm going to test out the cheaper stuff, in a gearbox I just fitted at the weekend. It has half the KMs of the car. If I get any crunching I'll go to the more expensive gear.

[sambb]

hang on. just checked my spare MTL container and its 70W80. Nulon smooth shift synthetic which is going in when the KAAZ LSD box goes in is 75W85W.

[Stein]

Cheers for all the responses lads. I went with the Nulon 75W-90 and in my brief test gear changes did seem a tiny little bit smoother but I had no issues before and it could have been my imagination.

If anyone needs the same gasket I think VW's code is 02R301215A. Not 100% on that so I snagged a photo of its label. If someone can confirm I'll add it to the OP.


Finally got some time to do the swap yesterday, low and behold the old gasket was completely fine. Turns out the issue was that the bottom left bolt hole is almost completely stripped, the bolt holds in there by the skin of its teeth but there's no way I can get the 18NM required on it.



I'm thinking that I'll drill the hole out and put one of those threaded inserts in, if I try and use a larger bolt I'd have to modify the cover and having mismatched bolts would keep me up at night.

If anyone has a better idea than the threaded insert I'd be glad to hear it, not super excited about having to take drill to it.


Thanks again all.

[h100vw]

Helicoil will work fine. Don't worry. Just be really careful as you're drilling. Otherwise a painless process